The battery in the Praktica Super TL3 is only for the light meter. The shutter is totaly mechanical. From what you discribe above it does sound like the poor thing has died.
Repair would be expensive compared to the price of another camera. I would suggest you keep the lens and get another body. As far as I know the TL series of Prakticas had a very sturdy shutter and give years of good service, dispite what some people say about Prakticas. I have had a few MTL 3's and MTL5's pass through my hands and they all worked perfectly, the only problem I had with them was the light seals perrished. I fitted new light seals using the felt strip from used film cassettes.

Last year I uncovered my 1st SLR I bought when I was 16, in the attic, a Praktica Super TL. I cleaned it and the shutter worked perfectly (26 years after it was put in the attic) even though it's the older cloth type shutter. BTW the camera is 37 years old so it just show you that they are good.